In general, a turbojet engine nacelle comprises an air intake structure, a middle section and a downstream section. The term “downstream” here refers to the direction corresponding to the direction of the cold air flow penetrating the turbojet engine. The term “upstream” designates the opposite direction.
The air intake structure is situated upstream of the turbojet engine serving to propel the aircraft and includes a so-called laminar mobile cowl frequently designated by LFC (“Laminar Forward Cowl”). Downstream of the air intake structure, the middle structure is intended to surround a fan of the turbojet engine. Still further downstream is the downstream section generally housing thrust reverser means intended to surround the combustion chamber of the turbojet engine. The nacelle ends with a jet nozzle whereof the output is situated downstream of the turbojet engine.
The air intake structure comprises, on the one hand, an air intake lip and, on the other hand, a downstream structure on which the lip is attached. The air intake lip is adapted to allow optimal collection towards the turbojet engine of the air needed to supply the fan and internal compressors of the turbojet engine. The downstream structure is intended to suitably channel air towards the vanes of the fan. This downstream structure generally has an outer panel or cowl and an inner panel. The inner panel has an acoustic shroud making it possible to attenuate the noises created by the turbojet engine as well as the vibrations of the structures.
A majority of equipment such as the accessory gear box (AGB) can be mounted on a turbojet engine body, situated downstream of a case belonging to the middle structure and intended to surround the fan of the turbojet engine. A minority of equipment is mounted around the aforementioned fan case, such equipment being able to be mounted around the aforementioned fan case, such equipment for example being able to be electronic housings or an oil reservoir. The latter are arranged at the downstream end of the fan case, more precisely on an intermediate case dimensioned to support such equipment.
A frequent maintenance operation consists of filling the aforementioned oil reservoir.
To that end, it is known to provide a viewing port and an access hatch to the oil reservoir. The placement of such a hatch decreases the strength of the nacelle structure and increases the cost thereof.
Furthermore, to replace part of the internal equipment, it is generally necessary to place the entire air intake structure. This so-called placement operation consists of removing the air intake structure from the rest of the nacelle. To that end, it is necessary for the nacelle to be equipped with a system allowing the mobility of the air intake structure. Such a deposition requires heavy and substantial tools, and requires that the propulsion assembly and therefore generally the airplane be immobilized.
Document FR 08-00845 in the Applicant's name describes a system allowing such mobility.
More particularly, this document describes a turbojet engine nacelle comprising an outer structure including an annular lip defining an air inlet and a cowl extending as a continuation of the annular lip, and an inner fixed structure extending as a continuation of the air inlet and including a region equipped with at least one piece of equipment requiring maintenance or monitoring, the outer structure being able to move in relation to the inner structure between an operating position in which the cowl covers the region equipped with the equipment and a maintenance position in which the cowl reveals said region so as to allow access to the equipment from outside, the outer structure being equipped with at least one reinforcing beam designed to transmit loads between the annular lip and the cowl, said beam extending in the radial plane of the air inlet from the outer structure towards the inner structure and comprising guide means capable of co-operating with complementary guide means belonging to the inner structure.
The complementary guide means are formed by rails cooperating with guide members mounted on the beams. Each rail is mounted under the beam and extending along the longitudinal axis of the nacelle. Openings or recesses allowing the passage of the rails are formed in the beams, at the points of intersection between each rail and the corresponding beam.
Such recesses or openings weaken the strength of the beams, also called inertia.
It will be recalled that each beam extends along the longitudinal direction of the nacelle, but also along a radial direction, i.e. towards the center of the nacelle, ideally as close as possible to the fan case. However, the rails, the guide members and the fittings making it possible to fasten these components are housed between the beams and the fan case, which limits the dimensions of the beams along the corresponding radial plane.
Thus, the rigidity of the beams is also limited, the latter depending directly on the dimension of the beams along the aforementioned radial plane.